Abstract Congenital muscular dystrophies (CMDs) with brain malformations are genetic diseases. Brain malformation involves movement of neurons out of the cerebral cortex through breaches of the pial basement membrane (PBM). We propose to study the critical molecules underlying formation of the PBM by radial glia. O-mannosyl glycosylation appears to have an important role. Also further studies of POMT2 conditional knockout mice may shed light on disruptions of the PBM that mediate migration of cells out of the brain. Our hypothesis is that radial glia have a key role in assembling the PBM. Specific Aims are to investigate: 1. The role of radial glia in assembly of the pial basement membrane (PBM). 2. The mechanisms of PBM abnormalities in POMT2 knockout mice. 3. The feasibility of using Large in gene therapy. The proposed research will provide new and important insights into how protein O- mannosyl glycosylation regulates the formation and maintenance of the PBM. It should also yield insights on mechanisms underlying brain malformations in type II lissencephaly. Better knowledge of the key molecules involved in PBM disruptions should lead to potential gene therapies. Gene delivery to restore protein functions should be directed at those cells that organize the formation of the PBM. The proposed research should lead to an improved understanding of the pathogenesis of muscular dystrophies in general and their treatment. 1